Cross-national comparisons of the occurrence of Alzheimer's and vascular dementias

The relative occurrence of Alzheimer's and vascular dementias is examined in various countries using data of four types: incidence, prevalence, clinic and neuropathological studies. There is clear evidence that Alzheimer's dementia is more common than vascular dementia in Great Britain and North America and, to a lesser extent, in Scandinavia. The evidence from other countries with predominantly Caucasian populations is more limited, but also supports a predominance of Alzheimer's dementia. By contrast, the evidence from Japan generally shows that vascular dementia is more common. The more limited evidence available from China also supports a preponderance of vascular dementia. There is a need for studies directly comparing the occurrence of Alzheimer's dementia in Caucasian and Oriental populations.

[Neuropathologic validation of clinical diagnosis of senile dementia of the Alzheimer type]

The purpose of this work was to establish a neuropathological confirmation of the clinical diagnosis of senile dementia of the Alzheimer type (SDAT) in a group of patients prospectively studied in a geriatric hospital since 1984 (Charles Richet Study). The sample consisted of 45 cases, 35 of which had received a clinical diagnosis of SDAT and 10 others a diagnosis of either vascular or mixed dementia. The mean age at death was 85 +/- 6.9 years (range 64-97). The neuropathological diagnosis was established independently of the clinical findings. Senile lesions typical of SDAT were found in 32/35 cases, giving a 91.4% rate of clinico-pathologic agreement. However, vascular lesions were present in 10 cases (28.5%) and the final pathologic diagnosis was mixed dementia, lowering the score of agreement for SDAT to 63%. Considering that the pathological criteria for the diagnosis of SDAT are not uniform, we independently applied 3 inclusion (senile lesions) and 3 exclusion (vascular lesions) criteria for the diagnosis of SDAT to each of the 45 cases. This permitted a comparison of nine combinations of neuropathological criteria with the clinical diagnosis. The sensitivity values ranged from 37 to 80% and the specificity values ranged from 55 to 100%. The highest agreement rate with the clinical diagnosis was achieved when were associated the criterion which specified that plaques and tangles must be present in the hippocampus regardless of neocortical findings and the criterion which excluded cases with vascular lesions of any site if their volume was 50 ml or more.(ABSTRACT TRUNCATED AT 250 WORDS)

[The significance of cerebral white matter lesions in vascular dementia--from psychiatric aspects]

The significance of cerebral white matter lesions in vascular dementia was mentioned, based on the findings of 50 autopsied cases at Yokuhukai Geriatric Hospital. Neuropathology of vascular dementia is classified to 5 types, i.e. 1) lacunar type, 2) cortical type, 3) cortico-white matter type, 4) white matter type, and 5) Binswanger type. Our findings on 50 patients revealed no lacunar type, cortical type in 8 cases, cortico-white matter type in 19, white matter type in 9, and Binswanger type in 14. The fact that 42 patients out of 50 showed some lesions involving the cerebral white matter suggested the important role of the white matter lesions in the pathogenesis of dementia of vascular type. Our cases also indicated that Binswanger type be commonly observed, although dementia of this type has been thought to be very rare since Binswanger (1894) and Alzheimer (1902) had reported similar patients. The patients with cerebral white matter lesions develop more marked dementia, especially of frontal and parieto-occipital type, than ones with cortical lesions, but the characteristics of symptoms of white matter and Binswanger type remain to be fully clarified.

[Clinicopathologic study of progressive subcortical vascular encephalopathy of Binswanger type (PSVE)]

To investigate the histopathological basis of white matter pallor on myelin staining in PSVE, the frontal white matter was examined by electron microscopy in 7 cases with PSVE. The number of nerve fibres per unit area of the white matter was significantly less in PSVE compared with that in the control group or in senile dementia of Alzheimer's type (SDAT). Nerve fibers in PSVE had a tendency to have thinner myelin sheaths than in the control group or in SDAT, but the difference was not significant. The white matter pallor in PSVE is mainly based on the loss of nerve fibres. The dementia in PSVE is probably related to the loss of nerve fibres in the cerebral white matter. A sum of oligodendrocytes and astrocytes per unit area decreased in the area with white matter pallor. Main stem of cerebral arteries, leptomeningeal arteries, medullary arteries in the cortex, and small arteries or arterioles in the cerebral white matter were studied pathologically in 22 elderly patients with PSVE. Not only the severe hyalinotic changes of arterioles in the cerebral white matter, but also the diffuse atherosclerotic lesions in main stem of cerebral arteries and/or the stenotic lesions in leptomeningeal arteries were the characteristic arterial changes of PSVE. Angionecrosis was observed in 70% of the PSVE patients. To substantiate my hypothesis that PSVE in the elderly can be induced by the repeated hypotension or the greater variability of the casual blood pressure in the hypertensives, I studied retrospectively the casual blood pressures in PSVE.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical diagnosis of Binswanger's disease

To aid in the prospective study of Binswanger's disease, a poorly understood form of vascular dementia, a standardised criteria for its antemortem diagnosis was proposed. These criteria include dementia, bilateral radiological abnormalities on computed tomography (CT) or magnetic resonance imaging (MRI), and at least two of the following three clinical findings: A) a vascular risk factor or evidence of systemic vascular disease; B) evidence of focal cerebrovascular disease; and C) evidence of "subcortical" cerebral dysfunction. These criteria were validated in two ways. First, by retrospectively applying them to a series of 30 demented patients with various pathological diagnoses. Second, by prospectively applying them to a series of 184 patients with clinically typical Alzheimer's disease. The sensitivity and specificity of the criteria appear adequate for use in clinical research.

[Etiology and pathology of 71 dementia patients during presenile and senile periods]

Etiological and pathological findings in 71 patients with dementia during presenile and senile periods were reported. According to the etiological findings these were divided into: vascular dementia (41), Alzheimer's disease (13), Pick's disease (1), Parkinsonian dementia (5), progressive supranuclear palsy (1), Huntington's disease (2), syphilitic general paralysis (2), chronic epidural hematomas (2), normal pressure hydrocephalus (1), brain tumor (1), cerebral cysticercosis cellulosae (1), hypoparathyroidism (1), and 1 case of dementia after stereotactic operations for parkinsonism. In this series, vascular dementia and Alzheimer's disease were obviously more frequent. The authors think that it might be difficult to differentiate cortical from subcortical dementia in every demented patient. They also suggest that the term arteriosclerotic dementia should cease to be used.

Vascular dementia

Vascular dementia is almost always associated with organic brain lesions due to ischemia, not with arteriosclerosis alone. In Japan, more than 50% of dementia in population older than 65 years are of vascular origin. Vascular dementia occurs with diffuse vascular lesions in the cerebral white matter or circumscribed lesions in particular areas such as the thalamus, anterior limb of the internal capsule, and cingulate gyrus, all of which constitute the ascending activating system or the limbic system. Vascular dementia is clinically characterized by stepwise progression, fluctuating course and predominant deterioration of intelligence with relative preservation of personality. Reversibility, disproportionate impairment of intelligence and personality, and dementia caused by a focal lesion observed in vascular dementia pose problems with regard to the classical concept of dementia. The similarity and difference between remitting dementia and disturbance of consciousness remain to be scrutinized.

[A clinical study on the usefulness of CT and MRI imaging in evaluating differential diagnosis and the degree of dementia in vascular dementia]

For the evaluation of differential diagnosis and estimation of the functional prognosis for vascular dementia (VD), the usefulness of computed tomography (CT) and magnetic resonance imaging (MRI) in detecting cerebro-vascular lesions was compared. Then the correlations between the degrees of mental function (Hasegawa's dementia rating scale: HDRS, activity of daily living: ADL, troublesome behaviors: TB) and the CT findings of vascular dementia were examined retrospectively. A hundred and seventeen dementia patients (male: 79 cases, female: 38 cases; mean-age 69.5 +/- 10.9 years old), diagnosed using DSM-III criteria, were scored according to Hachinski's ischemic score (I.S.) by clinical course and symptoms. Both MRI and CT were carried out on 56 dementia cases (male: 21 cases, female: 35 cases; mean-age 78.0 +/- 7.4 years old) at the chronic stage of the cerebro-vascular accidents to compare the detectiveness of vascular lesions. In 90 vascular dementia patients on whom only CT was carried out, the imagings were classified according to number, size, and localization. The correlation between these parameters and the degree of dementia were examined retrospectively. MRI was more useful and sensitive than CT for differentiating VD from DAT (dementia of Alzheimer type), since MRI was superior to CT in detecting small infarcts or lacunaes on the perforating area or white matter. Cases with positive findings on CT or MRI but clinically diagnosed as DAT by I.S. showed poorer ADL.(ABSTRACT TRUNCATED AT 250 WORDS)

[Vascular (arteriosclerotic) and Alzheimer's dementia in neurologic-psychiatric patient sample]

Despite the obviously more important degeneratively conditioned dementias, particularly of the Alzheimer-type, dementias due to vascular disorders are still of considerable relevance. They are even predominant among autopsies in a neurological-psychiatrical hospital, showing, however, a decreasing tendency. Though this cannot reflect the real incidence of a disease, because many cases of dementia die in geriatric or nursing homes, mostly not autopsied, exact epidemiological examinations of autopsy-cases seem to be advisable, limited temporarily and locally for economic reasons. Topographical specialities and modern methods of investigation in living persons increasingly enable a differentiation of vascular and degenerative dementias and thus frequently an effective treatment.

[Multi-focal delayed neuronal damage after transient regional ischemia--mechanism of vascular dementia]

We describe multi-focal delayed neuronal death of rat brain after transient regional ischemia induced by embolization of the right middle cerebral artery (MCA). After sixty minutes of MCA occlusion, recirculation was achieved by removal of the embolus. Chronological changes in the distribution of the neuronal damage were determined by using the 45Ca autoradiographic technique and the histological examination. Sixty minutes after MCA occlusion, 45Ca accumulation extended to the lateral segment of the caudate putamen and the cerebral cortex supplied by the occluded MCA. Moreover, three days after ischemic insult, 45Ca had accumulated in the ipsilateral thalamus and substantia nigra. Histological examination revealed that the neurons in both area suffered damage and were selectively reduced in number. Both areas lie outside the ischemic area, but have transsynaptic connections with the ischemic focus. We suggest that the postischemic delayed neuronal death in exo-focal remote areas may be caused by a transsynaptic process associated with the infarcted areas and that these delayed multi-focal brain damage may exacerbate clinical symptoms in the chronic stage of stroke.

Clinicopathological analysis of dementia disorders in the elderly

The relative incidence of the major types of dementia disorders and the agreement rates between clinical and pathological diagnosis were analysed in consecutive autopsy series of 675 demented subjects from 3 hospitals (mean age 79.5 years, SD 9.6). Clinical assessment followed the DSM-III and ICD-9-NA criteria and NINCDS/ADRDA criteria for probable Alzheimer disease (AD) (McKhann et al. 1984), histological criteria for the diagnosis of AD those of the NIH/AARP Work Group (Khachaturian 1985) using a 4-degree rating scale for plaques and tangles in neocortex and hippocampus (Morris et al. 1988), and the criteria by Tierney et al. (1988) for 'pure' AD. Vascular dementia (MID) and other disorders were diagnosed according to current pathologic criteria. Clinical diagnosis of AD/SDAT was made in 59.2%, of MID in 21.7%, of mixed AD + MID in 3.1%, and of Parkinson's disease (PD) and other disorders in 16%. At autopsy, 76.7% fulfilled histological criteria for AD/SDAT, but only 60% were 'pure' forms, while 8.2% had additional features of PD and 7.9% coexisting vascular lesions indicating mixed SDAT + MID. 15.7% were MID with no or very little AD pathology, 7.4% other CNS disorders. 0.3% of the brains showed no abnormality beyond age-related changes. AD/SDAT had its highest incidence in a psychiatric population, MID and PD + SDAT in general and geriatric hospital cohorts. The overall coincidence rates for clinical and pathological diagnosis of AD/SDAT were 85.2%, for MIX and MID 60.5-61.9%, but only 51% for PD-PD/AD. These data and the results of other recent studies emphasize the need for more appropriate clinical and pathological criteria in the diagnosis of the dementias.

[A case of Binswanger disease with numerous diffuse plaques in the neocortex]

A case of Binswanger disease with numerous diffuse plaques in the neocortex was reported. This male patient had a previous history of hypertension and myocardial infarction. From the age of 60, he developed dysarthria, bradykinesia, marche à petit pas and falling down. Neurological examination at his first admission disclosed muscular rigidity and increased jaw and deep tendon reflexes, but dementia was not found. Brain CT showed moderate brain atrophy and EEG consisted of slow wave dysrhythmia. He was diagnosed of Parkinsonism and treatment started without effects. During his second admission for the treatment of myocardial infarction, at the age of 64, delirium developed. Progressive dementia began and finally he was confined to bed. From the age of 69, spontaneous speech became almost lost. Contracture of the extremities, increased deep tendon reflexes and force grasping were noted. Brain CT showed symmetrical low attenuation in the frontal and parietal white matter with moderate dilatation of the lateral ventricles. At the age of 70, he died of general prostration about ten years after the initial symptoms. Neuropathological findings: Macroscopic findings: The brain weighed 1300 g. Atherosclerotic changes of the large arteries at the base of the brain were moderate. Coronal sections of the brain showed moderate enlargement of the lateral ventricles with multiple small lacunes in the basal ganglia. Microscopic findings: Bilateral diffuse demyelination of the white matter with sparing of the U-fibers was noted. Holzer stain revealed fibrillary gliosis in the left parietal and occipital white matter. Marked adventitial fibrosis of the deep white matter arteries and terminal stages of hyalinosis of the perforating arteries were found. Basal ganglia showed status lacunaris. Bilateral pyramidal tracts were atrophic secondly.(ABSTRACT TRUNCATED AT 250 WORDS)

Loss of nerve fibres in the corpus callosum of progressive subcortical vascular encephalopathy

The nerve fibres of the corpus callosum were studied by electron microscopy in five elderly patients with progressive subcortical vascular encephalopathy (PSVE) and compared with those in six age-matched controls. The number of nerve fibres per unit area of the corpus callosum was decreased in PSVE by 18-26%. The loss of nerve fibres in the corpus callosum can play a role in inducing the cognitive deficit of PSVE, on the basis of the loss of nerve fibres in the cerebral hemispheres.

[Brain atrophy: radiological-neurological correlations]

Computerized tomography of the head was done in 5021 patients aged 21 to 81 years from various neurological, neurosurgical and neurotraumatological indications. Brain atrophy as an only finding (primary) was noted in 11.5%- and in 5.4% of cases it was associated with other changes. The neurological-radiological correlations were established in 200 cases of primary strophy. History data included: headaches in 54.5%, dizziness in 15.0%, epilepsy in 24.5%. Objective examination showed: slight hemiparesis in 37.5%, spastic-atactic gait disturbances in 31.5%, isolated damage to the corticospinal tracts with signs limited to one side of the body was more frequent in cortical atrophy, and these signs associated with ataxia were more frequent in subcortional atrophy. The authors explain this as a loss of cortical cells or damage to the paraventricularly coursing nerve fibres. A probable aetiology of "primary" atrophy was established in 405% of cases (hypertension, atherosclerosis, minor craniocerebral trauma). No signs or neurological syndromes were observed which could be regarded as more or less characteristic of brain atrophy.

[Approach to the dementia research]

Main causes of dementia in the elderly are vascular dementia and Alzheimer's dementia. Vascular dementia is related to both amounts and localization of lesions. Recently incidence of diffuse vascular leukoencephalopathy (Binswanger type, leukoaraiosis) and amyloid angiopathy are increasing. In Alzheimer's protein chemistry of amyloid (beta protein, A4 protein) revealed its precursor APP and its gene (chromosome 21), which produces protease inhibitor in the brain of Alzheimer and Down's brains. APP is considered as an membrane protein (receptor) and appears abundantly in the cerebral cortex. Immunohistochemical study showed that beta protein is observed also in normal aged brain. On the other hand, tau protein (main component of Alzheimer's neurofibrillary tangle, PHF) appeared as abnormal sprouting of neurites in Alzheimer's brain. The latter may related to dementia and neural death. In Alzheimer's dementia, several neurotransmitters, including acetylcholine, are reduced in the brain and related structural changes are observed. Recently olfactory bulb and mucosal changes are remarked as one of pathogenesis of this disease. Delayed neuronal death is a new phenomenon of nerve cell death of vascular origin and should be studied in human vascular dementia.

Decrease in nerve fibres in cerebral white matter in progressive subcortical vascular encephalopathy of Binswanger type. An electron microscopic study

To study white matter changes in the frontal lobes and to investigate the histopathological basis for the dementia in progressive subcortical vascular encephalopathy (PSVE), the frontal white matter was examined by electron microscopy in seven cases with PSVE, and compared with that in a control group and in cases with senile dementia of Alzheimer's type (SDAT). The number of nerve fibres per unit selected area of the white matter was significantly less in PSVE compared with that in the control group or in SDAT. Nerve fibres in PSVE had a tendency to have thinner myelin sheaths than in the control group or in SDAT, but the difference was not significant. The pallor of the frontal white matter in PSVE is mainly based on the loss of nerve fibres, and may be in part based on the thin myelin sheaths. The dementia in PSVE is probably related to the loss of nerve fibres in the cerebral white matter.

[Cerebrovascular dementia; correlation of computed and histopathologic findings]

Computed tomography is often insensitive to such lesions as atrophic demyelination, enlarged perivascular spaces and infarction in the periventricular white matter. In attempt to better understand the discrepancy between the pathologic and X-CT findings, the author correlated areas that had focal, patchy on X-CT and brains with gross and microscopic findings. Patients with cerebral strokes had larger volume infarcts characterized centrally by necrosis, axonal loss, and demyelination. The progressive subcortical vascular encephalopathy (Binswanger's disease) is characterized by ischemic demyelinization of white matter provoked by hypertensive vascular changes in small vessels and is usually accompanied by multiple lacunar infarcts in a periventricular area and the basal ganglia. Small, deep hemispheric infarcts may be of no clinical significance unless a sufficient aggregate of these occurs. It should be pointed out that many small infarcts are clinically silent, and chronic multifocal ischemia may be responsible for observed senescent changes in cerebral tissue. The extension of the infarcted area might be most important in the development of cerebrovascular dementia. Mixed forms of degenerative dementia and any type of cerebral vascular disease are common and account for 10-20% of all dementias.

Computed tomography, magnetic resonance imaging and pathological correlations in a case of Binswanger's disease

The results of 3 computed tomography (CT) examinations carried out over a 7 year period and of a post-mortem magnetic resonance (MR) study showed aspects of a white matter disease in a hypertensive patient suffering from vascular dementia. Histopathology revealed the primary cause of dementia to be a white matter degeneration sparing the U fibers. Rarefaction of both the myelin sheaths and the axons was present together with severe thickening of the medullary arteries. These findings support the existence of Binswanger's disease (BD) as a distinct variety of arteriosclerotic dementia. CT and MR imaging are valuable aids for diagnosis. However, since there are many other causes of CT and MR demonstrated diffuse white matter degeneration in the elderly, a conclusive diagnosis of BD requires pathological confirmation.

[A semiquantitative study on Alzheimer neurofibrillary tangles demonstrated immunohistochemically with anti-tau antibodies, in the brains of non-demented and demented old people]

Submitted for the study were 116 autopsy brains, from 65 non-demented people, 24 patients with dementia of Alzheimer type (DAT) and 27 patients with vascular dementia, aged between 50 s and 100 s. Formalin-fixed, paraffin-embedded coronal sections of the brains at the level of the lateral geniculate body were immunohistochemically stained with the avidin-biotin-peroxidase complex procedure, using the anti-bodies to tau protein purified from human brains (anti-tau) as the primary antibodies. Alzheimer neurofibrillary tangles (NFTs) which were specifically and selectively stained by anti-tau were semiquantitatively counted in the areas of the hippocampus, parahippocampal gyrus and lateral occipitotemporal gyrus. The results were as follows: 1) In non-demented subjects, NFTs in the hippocampus and parahippocampal gyrus were scanty in the 50 s: they increased markedly after 60 years until 90 as the patients' age increased; they tended to decrease over 90 years. In contrast, NFTs in the lateral occipitotemporal gyrus remained none or scanty, always less than 10/mm2 field, throughout the ages between 50 s and 100 s. 2) In DAT cases, NFTs in the hippocampus and parahippocampal gyrus were numerous in all cases at any ages. NFTs in the lateral occipitotemporal gyrus were also many, and always more than 10/mm2 in all cases except a few ones over 80 years of age. The numbers of NFTs of the three areas were significantly higher in DAT cases than in non-demented subjects. 3) In most cases of vascular dementia, the density and distribution pattern of NFTs were essentially similar to those of non-demented subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Neurotransmitter deficits in a non-multi-infarct category of vascular dementia

Brain tissue from 9 severely demented patients cared for in psychiatric long-term wards and with records of stroke episodes, macroscopic signs of brain infarcts and with no clinical evidence of senile dementia of the Alzheimer type was investigated and compared with control material. The mean volume of the brain infarcts in this vascular dementia group was only 6.8 ml. Pronounced disturbances of the serotoninergic and cholingergic systems were found in subcortical and cortical grey matter. These widespread neurotransmitter changes can hardly be explained by the localized brain infarcts per se, but suggest the existence of another category of vascular dementia. Since the neurotransmitter disturbances were found to be similar to those of Alzheimer's disease and senile dementia of the Alzheimer type, it seems more likely that they indicate a common pathway for dementia disorders than that they serve as markers of different dementia categories.

[Acetylcholinesterase activity in CSF in senile dementia of Alzheimer type, vascular dementia, and Parkinson's disease]

Acetylcholinesterase (AChE) activity was measured in cerebrospinal fluid (CSF) from 25 patients with senile dementia of Alzheimer type (SDAT), 11 patients with vascular dementia (VD), 26 patients with Parkinson's disease (PD), and 30 normal controls. AChE activity also was measured in 46 normal subjects whose ages ranged from 15 to 85 to evaluate the effect of age on AChE activity. CSF AChE activity for the SDAT, VD and PD groups showed no significant difference compared with the value for the control group. However, there were significant decreases in CSF AChE activity in the VD and PD groups with the development of ventricular enlargement. There was no significant correlation between CSF AChE activity decrease and ventricular enlargement in the SDAT group. AChE activity increased significantly over the age range of 15 to 85. These results suggest that, although CSF AChE activity is not a useful parameter in the diagnosis of dementia, it may be a marker indicating abnormalities of the intracerebral cholinergic system during the process of cerebral atrophy.